chore(escrow): align Quasar and Anchor escrow naming for side-by-side comparison

[mikemaccana-edwardbot]

What and why

Mike's writing an Anchor-vs-Quasar comparison doc. The two implementations had diverged cosmetically: Anchor had already been refactored to canonical names (make_offer/take_offer/cancel_offer, Offer state, token_mint_a, maker_token_account_a, etc.), but Quasar still used the older make/take/refund with Escrow state and mint_a/maker_ta_a-style fields. Those surface-level differences make it hard to compare framework syntax without also tracking name differences.

This PR renames the Quasar program to match Anchor.

Renames in Quasar

Category	Before	After
Handler	make	make_offer
Handler	take	take_offer
Handler	refund	cancel_offer
Account struct	Make (+ MakeBumps)	MakeOffer (+ MakeOfferBumps)
Account struct	Take (+ TakeBumps)	TakeOffer (+ TakeOfferBumps)
Account struct	Refund (+ RefundBumps)	CancelOffer (+ CancelOfferBumps)
State type	Escrow	Offer
Field	mint_a	token_mint_a
Field	mint_b	token_mint_b
Field	maker_ta_a	maker_token_account_a
Field	maker_ta_b	maker_token_account_b
Field	taker_ta_a	taker_token_account_a
Field	taker_ta_b	taker_token_account_b
Field	vault_ta_a	vault
Field	escrow (state account field)	offer
File	src/instructions/make.rs	make_offer.rs
File	src/instructions/take.rs	take_offer.rs
File	src/instructions/refund.rs	cancel_offer.rs
Internal helper	handle_make_escrow	handle_make_offer
Internal helper	handle_withdraw_tokens_and_close_refund	handle_withdraw_tokens_and_close_cancel_offer

The internal helper renames pair each helper with its public handler: handle_make_offer with make_offer, handle_withdraw_tokens_and_close_cancel_offer with cancel_offer. "Refund" and "escrow" are dead as verbs/nouns in the rename spec.

Breaking change: PDA seed

The PDA seed for the offer state account changes from b"escrow" to b"offer" in the Quasar program, matching Anchor. This alters PDA derivation. This is an example program with no deployed users, so the alignment with Anchor is worth the seed change.

No renames needed in Anchor

The Anchor program (tokens/escrow/anchor/programs/escrow/) was already canonical: make_offer/take_offer/cancel_offer handlers, MakeOffer/TakeOffer/CancelOffer structs, Offer state, token_mint_a/token_mint_b/maker_token_account_a/etc. fields, b"offer" seed. Nothing changed on the Anchor side.

Deliberately not renamed

• Crate / directory names (tokens/escrow/anchor/programs/escrow/, tokens/escrow/quasar/). The program is called "escrow"; the state inside is called "Offer". Both correct.
• Other internal helpers — handle_deposit_tokens, handle_transfer_tokens, handle_withdraw_tokens_and_close_take. These are framework-neutral or already pair cleanly with their public handler.

Verification

$ cd tokens/escrow/anchor && cargo check
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.80s

$ cd tokens/escrow/quasar && cargo check
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.46s

$ cd tokens/escrow/quasar && cargo check --tests
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.33s

(Quasar emits warning: fields ... are never read for #[account] codegen — pre-existing, not introduced by this PR.)

git grep -E '\b(Make|Take|Refund|Escrow|mint_a|mint_b|maker_ta_a|maker_ta_b|taker_ta_a|taker_ta_b|vault_ta_a|handle_make_escrow|handle_withdraw_tokens_and_close_refund)\b' tokens/escrow/quasar/ → 0 matches.

Follow-up

None. Self-contained.